从 Gulp 3 升级到 Gulp 4

Question

I've attempted to update the gulpfile below to Gulp v4 from v3 but am still getting an error: AssertionError [ERR_ASSERTION]: Task never defined: client

Not sure what I am missing but realise that the functions may not be written correctly. The tasks in series are correct I believe: gulp.task('build', gulp.series('client', 'sass')); for example.

// gulpfile.js

var gulp = require('gulp'),
    concat = require('gulp-concat'),
    browserify = require('gulp-browserify'),
    rename = require('gulp-rename'),
    nodemon = require('gulp-nodemon'),
    sass = require('gulp-sass');


gulp.task('build', gulp.series('client', 'sass'));

gulp.task('watch', gulp.series('client-watch', 'sass-watch'));

gulp.task('server', function () {
  nodemon({
    script: 'server/index',
    ext: 'js json'
  });
});

gulp.task('client', function () {
  gulp.src('client/js/main.js')
      .pipe(browserify({
        transform: ['hbsfy'],
        extensions: ['.hbs']
      }))
      .pipe(rename('hearthclone.js'))
      .pipe(gulp.dest('./client/build'));
});

gulp.task('client-watch', function () {
  gulp.watch('client/js/**/*.js', ['client']);
});

gulp.task('sass', function () {
  gulp.src('client/**/*.scss')
    .pipe(sass())
    .pipe(concat('style.css'))
    .pipe(gulp.dest('client/assets/css'));
});

gulp.task('sass-watch', function () {
  gulp.watch('client/**/*.scss', ['sass']);
});


gulp.task('default', gulp.series('build', 'server', 'watch'));

Answer 1

When you use the gulp.task form of defining tasks (rather that as functions) then you cannot refer to those tasknames until after they have been declared. That would be a forward reference (see below). So just put your

gulp.task('build', gulp.series('client', 'sass'));

gulp.task('watch', gulp.series('client-watch', 'sass-watch'));

after all those tasks have been defined. I recommend right before the default task line.

See https://gulpjs.com/docs/en/api/series#forward-references

Forward references

A forward reference is when you compose tasks, using string references, that haven't been registered yet. This was a common practice in older versions, but this feature was removed to achieve faster task runtime and promote the use of named functions.

In newer versions, you'll get an error, with the message "Task never defined", if you try to use forward references. You may experience this when trying to use exports for your task registration and composing tasks by string. In this situation, use named functions instead of string references.